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Thursday, July 2nd, 2015

Jake gave a great talk at Responsive Day Out 3 all about nuanced progressive enhancement, with a look at service workers in particular (a technology designed with progressive enhancement at its heart).

To illustrate the performance gains, Jake used his SVGOMG site as an example—a really terrific resource for optimising SVGs.

SVGOMG requires JavaScript for its core functionality (optimising an SVG file). That was a deliberate choice. Jake could’ve made the barrier-to-entry as low as any browser that supports input type="file" but he decided that for this audience (developers) it was a safe assumption that JavaScript would be available.

I’m a strong believer in progressive enhancement, but also that each phase of the enhancement needs a user.

I agree completely with this approach. It makes sense to have a valid reason for adding any enhancement. But there’s something about this particular example that wasn’t sitting right with me. It took me a while to figure it out, but I now realise what it is.

Jake is talking about making it work on the server as an enhancement. But that’s not an enhancement, it’s a fallback.

Thinking in terms of fallbacks is more of a “graceful degradation” approach (i.e. for every “full” feature, thinking of a corresponding fallback). That’s not how I like to think of progressive enhancement. I like to think in terms of a baseline. And that baseline, in my mind, does not require a user to justify its existence. That’s because the baseline isn’t there to cover the use cases we can think of, it’s there to cover the use cases we can’t predict.

That might seem like a minor difference in wording to the graceful degradation approach but I think it’s actually a fundamentally different way of approaching the situation.

When I was on the progressive enhancement panel at Edge Conf, Lyza asked how low the baseline should be. I said “as low as possible.” Some of my fellow panelists took issue with this saying it varies from project to project, and that’s completely true, but I think I should’ve clarified that when I talk about a baseline, I’m not talking about browsers. I don’t think about a baseline in terms of “IE4 and above, Android 2.1 and above, etc.”—I think about a baseline in terms of “the minimum required technology to allow a user to accomplish the core task” (that qualification about core tasks is important—the baseline does not need to cover tasks that are nice-to-have; those can safely require more sophisticated technology).

That “minimum required technology” often turns out to be a combination of a web server, HTTP, and some HTML.

So to take SVGOMG as an example, I would begin with the baseline of “allowing a user to optimise an SVG file”. The minimum required technology is a web server running a programme that does the optimisation, and an HTML document that contains a form element with input type="file". Once that’s in place, then I can start applying Jake’s very sensible approach of thinking about enhancements in terms of specific user benefits. In this case, it’s pretty clear that 99.99% of the users would benefit from not having that round-trip to the server and have the SVG optimisation happen in the browser using JavaScript.

There’s an enhancement provided for the use case that I can imagine. But—and this is the subtle but important distinction—there’s a baseline for all the use cases that I can’t think of. I need to recognise that I won’t be able to predict all the possible use cases, and that’s okay—as long there’s a solid baseline in place, I’ve got an insurance policy for unforeseen circumstances. It’s still not perfect, but it lowers the risk somewhat by reducing the number of assumptions being built in at that baseline level.

Going back to Jake’s chat with Paul, he says:

I thought about making the site work without JS by doing the SVG work on the server, but this would be slow and a maintenance burden.

It is in theory possible to write a web app which does processing on the server and is entirely robust against its client-side scripting being broken or missing, and which does processing on the client so that it works when the server’s unavailable or uncontactable or expensive or slow. But let’s be honest here. That’s not an app. That’s two apps.

Leaving aside the promise of isomorphic/universal/whatever JavaScript, this issue of developer convenience is big issue. When I use the term “developer convenience” to label this problem, I am not belittling it in any way—developer convenience is incredibly important (hence the appeal of so many tools and frameworks that make life easier for developers). I still believe that developer convenience should be lower on the list of priorities than having a rock-solid baseline, but I can totally understand if someone doesn’t share that opinion. It’s a personal decision and if the pain involved in making a more universal baseline is greater than the perceived—and, let’s face it, somewhat abstract—benefit, I can totally understand that.

Anyway, that’s my little brain dump about progressive enhancement and baseline experiences. Something about treating the baseline experience as an enhancement was itching at my brain and now that I’ve managed to scratch it, I can see what was troubling me: thinking about the baseline experience in the same way as thinking about enhancements doesn’t work for me.

Personally, I’m going to strive to keep the baseline as low as possible. I’m also going to strive to apply Jake’s maxim about every enhancement requiring a user.